The intermediate approach to sustainability enhancement and scale -related measures in environmental assessment

Many studies have applied data envelopment analysis to environmental assessments. The approach measures the performance of various organizations with economic activities that use inputs to produce not only desirable (e.g., electricity) but also undesirable (e.g., CO2 emission) outputs. This study uses the method and discusses how to measure the level of sustainability, implying simultaneous achievement of economic prosperity and environmental protection within a unified framework. Conventionally, we classify this type of approach as either radial or non-radial. Recently, the intermediate approach, analytically located between them, has been proposed as the third alternative. This study discusses the methodological features of the intermediate approach. We focus in particular on its scale-related measures such as scale efficiency, returns to scale, and damages to scale. All of those measures can serve as new performance indicators for sustainability enhancement. As an illustrative example, we apply the proposed approach to assess the special districts of Tokyo and discuss those empirical results from the municipal planning. (C) 2019 Elsevier B.V. All rights reserved.